Electromagnetic relay

ABSTRACT

The present invention relates to an electromagnetic relay comprising:
         a base comprising at least one printed circuit card, which card has at least two conductor tracks forming respective switch accesses;   at least one conductive contact element movable between a closed position in which it presses against said two conductor tracks in order to establish an electrical connection between them, and an open position in which the contact element is spaced apart from at least one of said two tracks;   a contact element support, the support comprising at least one flexible arm carrying the contact element; and   an actuator mounted on the printed circuit card, and comprising at least one coil constituted by a winding of electric wires;   wherein the support includes at least one portion, in particular a portion in the form of a tongue, on which a moving member of the actuator acts in order to move said flexible arm of the support.

The present invention relates to an electromagnetic relay for use inparticular in the high frequency domain.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 4,839,619 discloses a relay comprising a substrate, suchas a printed circuit card having mounted thereon an assembly comprisinga rotor and a magnetic armature carrying an elastomer layer and adielectric layer. The dielectric layer has conductive strips suitablefor switching conductor tracks on the substrate. The rotor can be drivennot only in rotation about an axis perpendicular to the plane of thesubstrate, but it can also be moved axially along said axis. Since therotor needs to be capable of being driven alternately in rotation and intranslation, that relay presents a structure that is relatively complex,which can lead to a relatively high sale cost. That relatively complexstructure can also make it more difficult to provide a relay that iscompact and occupies only a small amount of space.

U.S. Pat. No. 6,081,176 discloses an electromagnetic relay comprising asystem of magnets, a base, a moving contact element, stationary contactelements, and terminal contact elements. The base is formed by twoprinted circuit cards leaving between them a space suitable forreceiving the moving contact element. The magnet system is not mountedon the base.

OBJECTS AND SUMMARY OF THE INVENTION

The invention seeks in particular to propose an electromagnetic relaythat is relatively compact, occupying little space, and of structurethat is relatively simple.

The invention provides an electromagnetic relay comprising:

-   -   a base comprising at least one printed circuit card, which card        has at least two conductor tracks forming two switch accesses;    -   at least one conductive contact element movable between a closed        position in which it presses against said two conductor tracks        in order to establish an electrical connection between them, and        an open position in which the contact element is spaced apart        from at least one of said two tracks; and    -   an actuator mounted on the printed circuit card, and comprising        at least one coil constituted by a winding of electric wires;        the actuator being arranged in particular to be capable of        moving the contact element solely in movement that does not        include a component in rotation about an axis perpendicular to        the plane of the printed circuit card.

By means of the invention, since the movement of the contact element canbe a single, elementary movement, such as a pivoting movement or amovement in translation, the actuator can present a structure that isrelatively simple.

The structure of the relay can be further simplified because the printedcircuit card serves as a support for the actuator.

This makes it possible for the relay to be made compact, to occupylittle space, and to present a small sale price.

The relay of the invention can be used for switching power that can begreater than 5 watts (W) and may be as great as about 200 W, at afrequency of 1 gigahertz (GHz), and in particular power of about 80 W.

In an embodiment of the invention, the relay further comprises a contactelement support, the support comprising at least one flexible armcarrying the contact element.

Advantageously, the support includes at least one portion, in particularin the form of a tongue, on which a moving member of the actuator actsin order to move said flexible arm of the support.

Under such circumstances, the support is independent of the movingmember, which can present the following advantages.

Firstly, assembly, handling, and storage of actuators is made easiersince they do not have a contact element, where contact elements can beparticularly fragile and sensitive to pollution. In addition, theactuators can be constituted by standard elements and can bepreassembled.

The actuators may also be assembled on different types of printedcircuit card, and can act on contact element supports of differentshapes.

The invention also makes it possible to secure a plurality of actuatorson a single printed circuit card using contact element supports ofdifferent shapes, thus making switching systems that are complex, and inparticular making switch matrices.

Furthermore, the contact and locking forces and the switching voltagesof the relay can be adjusted simply, merely by changing the distancebetween the actuator and the support.

The support may include at least one portion that is secured rigidly toa stationary portion of the relay.

This avoids friction between the support and said stationary portion ofthe relay, even when the flexible arm is being actuated, thus avoidingthe formation of dust or shavings.

The invention also enables the contact elements to be accuratelypositioned relative to the conductor tracks and improves therepeatability of such positioning.

Since the contact element is not secured to the moving member of theactuator, it is not subjected to operating clearance that appears in theconnection between the moving member and a stationary portion of therelay or of the actuator.

When there is a connection between the support and the moving member ofthe actuator, any variation in the position of the moving member duringeach switching operation gives rise to variation in the position of thecontact element relative to the conductor tracks.

Improved repeatability in the positioning of the contact elementguarantees excellent repeatability in microwave characteristics, inparticular in terms of insertion losses and standing wave ratio, whichcharacteristics are of great importance for measurement andinstrumentation applications.

The above-mentioned moving member may comprise an armature suitable forpivoting, e.g. about an axis parallel to the plane of the printedcircuit card.

The armature can be made as a single piece and/or can be substantiallyplane.

The support is preferably made as a single piece and is generallyflexible.

The support can be made of a conductive material and can carry aninsulating block arranged to insulate the contact element from thesupport.

This makes it possible to avoid short-circuit problems, and when therelay is used in the high frequency domain, it can avoid impedance beingdisturbed by the capacitive effect.

In an embodiment of the invention, the contact element comprises aconductive layer deposited on a first face of the insulating block,which block is secured to the support via a second face that is oppositefrom the first face.

In a variant, the contact element is constituted by a conductive bladeand the insulating block is obtained by overmolding on the support andthe blade.

In another embodiment of the invention, the support is made out ofinsulating material.

The contact element can then comprise a conductive layer deposited on aregion of the support.

In general, the invention makes it possible to connect the contactelement to the support without using an intermediate insulating partsecured in an orifice of the support and liable to generate shavings bythe part rubbing against the support.

In an embodiment of the invention, the support carries a pluralitycontact elements each associated with two switch accesses of the printedcircuit card.

In an embodiment, the contact element is not carried by a flexible arm,but by a moving member of the actuator.

The moving member may comprise a rod suitable for being moved axially,perpendicularly to the plane of the printed circuit card, or an armaturesuitable for pivoting about an axis parallel to the plane of the printedcircuit card, for example.

The contact element passes from the open position to the closedposition, or vice versa, without sliding on the printed circuit card.

The printed circuit card may carry at least one electricity power supplyconductor track that is electrically connected to said at least oneelectric coil. This connection can be implemented via a connectionmember that is separate from the coil or via a terminal of the coil.

The connection member may be arranged for being secured, in particularby soldering, in a hole of the printed circuit card, and it may comprisea pin with a slot in which a terminal of the coil can be engaged. Thecoil can be separate from the printed circuit card.

In an embodiment of the invention the base comprises a plurality ofprinted circuit cards that are stacked one on another and fastenedtogether, the conductor tracks of the cards possibly beinginterconnected via plated-through holes made through the thickness of atleast one of the cards.

The stack of printed circuit cards can form a stripline type structureenabling satisfactory performance to be obtained in the high frequencydomain.

By placing conductor tracks at a plurality of levels in the stack, it ispossible to implement switching functions that are more complex.

When the relay is of the surface mounting technology (SMT) type, atleast one of the conductor tracks may be connected to a conductive stripextending across the thickness of the printed circuit card, said strippossibly being made on an edge face of the printed circuit card, and inparticular being constituted by a metal-plated surface in a setback inthe edge face of the card, or it may be constituted by the metal-platedwall of a hole through the printed circuit card.

The metal-plated strips serve to enable connections to be made bysoldering between the conductor tracks on the relay card and the trackson the circuit or the card that is to receive the relay.

Such soldering can be particularly reliable since it can be performedbetween two printed circuit cards made of materials of the same kind andpresenting identical coefficients of thermal expansion.

In a variant, at least one of the conductor tracks is connected to asocket enabling a coaxial cable or a coaxial connector to be connectedthereto.

The printed circuit card can be made on the basis of glass epoxy or ofceramic.

In an embodiment of the invention, the relay includes a cover secured tothe printed circuit card, in particular by adhesive. It can berelatively easy to put the cover into place.

The relay may be of the single-pole double-throw (SPDT), double-poledouble-throw (DPDT), double-pole triple-throw (DP3T), single-poleN-throw (SPNT), or N-pole N-throw (NPNT) type.

The actuator may be of the monostable type or of the bistable type.

The invention also provides a method of manufacturing an electromagneticrelay as specified above, the base comprising a plurality of printedcircuit cards that are stacked on one another and fastened together, themethod comprising the following steps:

-   -   cutting out a plurality of printed circuit cards;    -   etching conductor tracks on the cards;    -   stacking the printed circuit cards; and    -   firing the stack of cards so as to perform sintering.

To implement the above-specified method, it is possible in particular touse the so-called “low temperature cofired ceramics” technique.

The invention also provides an electromagnetic relay comprising:

-   -   a base comprising at least one printed circuit card, which card        has at least two conductor tracks forming two switch accesses;    -   at least one conductive contact element movable between a closed        position in which it presses against said two conductor tracks        in order to establish an electrical connection between them, and        an open position in which the contact element is spaced apart        from at least one of said two tracks; and    -   an actuator mounted on the printed circuit card, and comprising        at least one coil constituted by a winding of electric wires;

wherein the printed circuit card further comprises at least one electricpower supply conductor track separate from the two conductor tracksforming switch accesses, and wherein the coil is connected to theelectrical power supply tracks.

The invention also provides an electromagnetic relay comprising:

-   -   a base comprising a plurality of printed circuit cards stacked        on one another and fastened together, at least one of the        printed circuit cards having at least two conductor tracks        forming two switch accesses;    -   at least one conductive contact element movable between a closed        position in which it presses against said two conductor tracks        in order to establish an electrical connection between them, and        an open position in which the contact element is spaced apart        from at least one of said two tracks; and    -   an actuator mounted on the base and including at least one coil        presenting a winding of electric wires.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood on reading the following detaileddescription of non-limiting embodiments, and on examining theaccompanying drawings, in which:

FIG. 1 is a diagrammatic and fragmentary exploded view of anelectromagnetic relay in accordance with the invention;

FIG. 2 is a diagrammatic and fragmentary view of the FIG. 1 relay afterthe actuator has been assembled on the printed circuit card;

FIG. 3 is a diagrammatic and fragmentary view of the card and of certaincomponents of the actuator of the relay of FIGS. 1 and 2;

FIGS. 4 and 5 are diagrammatic and fragmentary perspective views showinga contact element support in two different variant embodiments of theinvention;

FIG. 6 is a view analogous to FIG. 3 showing a relay in a variantembodiment of the invention;

FIG. 7 is a diagrammatic and fragmentary axial section view of a relayconstituting another embodiment of the invention;

FIGS. 8 to 10 are diagrammatic and fragmentary views of a relay base inanother embodiment of the invention, seen respectively from below, theside, and above;

FIGS. 11 to 14 are diagrammatic and fragmentary views showing variousswitch access dispositions of a relay in accordance with the invention;

FIG. 15 is a diagrammatic and fragmentary view of a relay in anotherembodiment of the invention; and

FIG. 16 is a diagrammatic and fragmentary view of a support in anotherembodiment of the invention.

MORE DETAILED DESCRIPTION

FIG. 1 shows an electromagnetic relay 1 in accordance with theinvention, comprising a base 2 constituted by a printed circuit cardmade on the basis of epoxy glass or ceramic, and an actuator 3 suitablefor being mounted on the printed circuit card 2.

The card extends in a plane defined by two perpendicular axes X and Y.

In the example described, the card 2 has three conductor tracks 4 a, 4b, and 4 c on its top face 2 a with the two tracks 4 a and 4 b forming afirst pair of switch accesses and the two tracks 4 b and 4 c forming asecond pair of switch accesses.

Each of the conductor tracks 4 a-4 c is connected at one end to aconductive strip 5 formed by plating metal on a setback 6 formed in anedge face of the card 2.

In the example described, the setbacks 6 are in the form ofhalf-cylinders of axis Z perpendicular to the plane of the card 2. In avariant, the setbacks 6 could be in the form of quarter-cylinders. Inanother variant, the conductive strips 5 could each be made on the wallof a hole through the card 2. These strips 5 may also advantageously bemade on a plane edge face of the card 2.

The conductive strips 5 serve to establish solder connections betweenthe conductor tracks 4 a-4 c and conductor tracks on another printedcircuit card that is to receive the relay 1.

The bottom face 2 b of the card 2 may be metal coated, thereby making itpossible, where necessary, to obtain satisfactory shielding and betterimpedance matching at high frequencies.

The card 2 also has four conductor tracks 8 a-8 d for feedingelectricity, each connected at one end to a plated-through hole 9 and atits other end to a conductive strip 5 as defined above enabling saidtracks 8 a-8 d to be connected to an electricity power supply.

Switching between the tracks 4 a & 4 b, or 4 b & 4 c respectively, isperformed by two conductive contact elements 10 each movable between aclosed position in which the corresponding contact element 10 pressesagainst the respective pair of tracks 4 a & 4 b or 4 b & 4 c, therebyestablishing an electrical connection between them, and an open positionin which the contact element 10 is spaced apart from said pair oftracks.

Each contact element 10 is constituted by a layer of conductive materialdeposited on a plane first face of an insulating block 11, which blockhas a face opposite from its first face secured to a generally flexibleconductive support 13.

The support 13 may be made of beryllium copper or of any other metal oralloy.

This support comprises two lateral portions 14 of axis Y, each providedwith an orifice 14 a for engaging on a support rod 15.

These lateral portions 14 are connected perpendicularly to a centralportion 17 of axis X having an orifice 17 a in its middle for engagingsaid portion 17 on a rod 15.

The central portion 17 has two slots 20 on either side of the orifice 17a.

The support 13 also has two flexible arms 21, each connected to thecentral portion 17 via a substantially rectilinear portion 22 of axis Y,extended by an end portion 23.

The end portion is substantially U-shaped, and of axis X when observedfrom above.

Connected to the portion 22, each arm 21 has a tongue 25 of axis X.

As can be seen in FIG. 1, the support 13 is axially symmetrical aboutthe axis Y.

Each insulating block 11 is secured to the outermost limb 23 a of theU-shape.

In the example described, the insulating block 11 and the correspondingconductive layer 10 are obtained by being cut out from a printed circuitcard carrying a conductor track.

The rods 15 are designed to have their bottom ends secured in orifices28 formed in the card 2.

In conventional manner, the actuator 3 comprises two coils 30, eachpresenting a winding of electric wires around a core, and serving toactuate a moving member that is constituted in the example described byan armature 31 that can be seen in FIG. 3.

The armature 31 is mounted on the actuator 3 in such a manner as topivot about the axis Y, being capable of pressing in alternation againstone or other of the tongues 25 of the support 13 so as to bend thecorresponding arm 21 and cause the contact element 10 to move downwardsin order to interconnect the tracks 4 a & 4 b, or 4 b & 4 c.

In an example not shown, the armature 31 may be replaced by members thatcan be moved linearly, parallel to the axis Z, each coming to pressagainst one of the tongues 25 of the support 13.

The actuator 3 has bottom and top walls 33 and 34 provided with orifices35 enabling the actuator 3 to be secured to the support rods 15, asshown in FIG. 2.

In the example described, each coil 30 has two terminals 36 projectingoutwards.

Each of these terminals 36 is electrically connected to a correspondingpower supply track 8 a-8 d via a respective pin 39.

Each pin 39 has a slot 40 in which a respective terminal 36 is engaged.

The bottom end of each pin 39 is secured in a plated-through hole 9 inthe card 2, e.g. by soldering.

Thus, the actuator 3 is powered electrically via the conductor tracks 8a-8 d, the pins 39, and the terminals 36.

This serves in particular to make the relay 1 more compact and to reduceits number of component parts.

In an example that is not shown, the terminals 36 of the coils 30 arearranged to be secured directly in the holes 9 in the card 2, withoutusing pins 39.

The relay 1 has a cover 42 suitable for being secured to the card 2 byadhesive.

In a variant, the support rods 15 are made integrally with at least oneof the bottom and top walls 33 and 34 of the actuator. In general, theactuator 3 can be secured to the card 2 in any appropriate way.

It would not go beyond the ambit of the present invention for thesupport carrying the contact elements to be made in some other way.

FIG. 4 shows a support 13′ that differs from the above-described support13 by the fact that each contact element is constituted by a conductiveblade 43 and the insulating block 44 is obtained by being overmolded onthe support 13′ and the conductive blade 43.

FIG. 5 shows a support 13″ constituting another embodiment of theinvention, which support 13″ is made of an insulating material, e.g.based on a ceramic. The contact element is constituted by a layer ofconductive material 45 deposited on one face of the limb 23 a of the endportion 23.

In the example described with reference to FIG. 1, the support hasportions that are rigidly secured to a stationary portion of the relay.

In a variant, as shown in FIG. 16, the relay may have a support 80 thatis flexible, carrying two contact elements 81 via two insulating blocks82, which support 80 is pivotally secured on two stationary studs 83.

In the examples described above, the contact elements are made on asupport that is generally flexible and that is moved by a moving memberof the actuator.

In a variant, the contact elements may be made directly on a movingmember of the actuator.

FIG. 6 shows an embodiment of the invention in which the contactelements are constituted by a conductive layer 46 deposited on twoarmatures 50 suitable for pivoting about the axis X.

In another variant, the contact elements may be carried by movingmembers 55 of the actuator that comprise pushers that are axiallymovable along the axis Z, as shown in FIG. 7.

The base of the relay may be constituted by a plurality of printedcircuit cards that are stacked on one another and fastened together.

As shown in FIGS. 8 to 10, the stack 60 of printed circuit cards 61 madeof ceramic material may carry conductor tracks 62 interconnected byplated-through holes 63 formed through the thickness of some of thecards 61.

The cards 61 situated in the top portion of the stack 63 may define acavity 65 having a bottom onto which there run conductor tracks 62forming switch accesses.

In particular, the stack of printed circuit cards makes it possible toobtain switching functions that are more complex.

In the example described, the stack is made using the low temperaturecofired ceramics technique.

FIGS. 11 to 14 show various possible positions for the switch accesses.

FIG. 11 shows a disposition having two accesses that are switchable by asingle contact element 10.

FIG. 12 shows a disposition having four accesses 4 that are switchableby four contact elements disposed in a lozenge configuration.

FIG. 13 shows a disposition having five accesses 4 that are switchableby four contact elements in alignment.

FIG. 14 shows a disposition having six accesses 4 that are switchable byfive contact elements disposed in a star configuration.

Naturally, the invention is not limited to the embodiments describedabove.

In the examples described above, the relay is of the CMS type.

In a variant, and as shown in FIG. 15, the relay may include sockets 70,each secured to one end of a conductor track 4 a-4 b.

These sockets 70 make it possible without using tools to connect coaxialcables or coaxial connectors.

The sockets described in French patent No. 2 786 613 in the name of theApplicant company can be used in the relay of the present invention.

These sockets serve to connect a stripped coaxial cable to a printedcircuit card.

The sockets 70 can be secured to the card 2 or they can be carried by aplate or a housing. The plate or the housing can also serve to provideprotection and/or strength to the relay and enable the relay to besecured to equipment. They may also serve as a support for connectionterminals for feeding electricity to the coils of the actuator.

1. An electromagnetic relay comprising: a base comprising at least oneprinted circuit card, which card has at least two conductor tracksforming respective switch accesses; at least one conductive contactelement movable between a closed position in which it presses againstsaid two conductor tracks in order to establish an electrical connectionbetween them, and an open position in which the contact element isspaced apart from at least one of said two tracks; a contact elementsupport, the support comprising at least one flexible arm carrying thecontact element; and an actuator mounted on the printed circuit card,and comprising at least one coil constituted by a winding of electricwires; wherein the support includes at least one portion, in particulara portion in the form of a tongue, on which a moving member of theactuator acts in order to move said flexible arm of the support, andwherein the support is made of a conductive material and carries aninsulating block to insulate the contact element from the support.
 2. Arelay according to claim 1, wherein the contact element comprises aconductive layer deposited on a first face of the insulating block,which block is secured to the support via a second face that is oppositefrom the first face.
 3. A relay according to claim 1, wherein thecontact element is constituted by a conductive blade and wherein theinsulating block is obtained by overmolding on the support and theblade.
 4. A relay according to claim 1, wherein the support is made ofan insulating material.
 5. A relay according to claim 4, wherein thecontact element comprises a conductive layer deposited on a region ofthe support.
 6. A relay according to claim 1, wherein the supportincludes at least one portion that is rigidly secured to a stationaryportion of the relay.
 7. A relay according to claim 1, wherein thesupport carries a plurality of contact elements, each associated withtwo switch accesses of the printed circuit card.
 8. A relay according toclaim 1, wherein the moving member comprises an armature suitable forpivoting about an axis parallel to the plane of the printed circuitcard.
 9. A relay according to claim 1, wherein the support is made as asingle piece.
 10. A relay according to claim 1, wherein the printedcircuit card has at least one electrical power supply conductor trackelectrically connected to said at least one coil.
 11. A relay accordingto claim 10, wherein said connection is implemented via a connectionmember fastened in a hole in the printed circuit card.
 12. A relayaccording to claim 11, wherein the connection member comprises a pinwith a slot in which a terminal of the coil can engage.
 13. A relayaccording to claim 1, wherein the base comprises a plurality of printedcircuit cards that are stacked on one another and fastened together. 14.A relay according to claim 13, wherein the conductor tracks of the cardare interconnected by plated-through holes made through the thickness ofat least one of the cards.
 15. A relay according to claim 1, wherein atleast one of the conductor tracks is connected to a conductive stripextending across the thickness of the printed circuit card.
 16. A relayaccording to claim 15, wherein said conductive strip is made on an edgeface of the printed circuit card, being constituted in particular by ametal-plated surface in a setback in the edge face of the printedcircuit card.
 17. A relay according to claim 15, wherein the conductivestrip is constituted by the metal-plated wall of a hole in the printedcircuit card.
 18. A relay according to claim 1, wherein at least one ofthe conductor tracks is connected to a socket enabling a coaxial cableor a coaxial connector to be connected thereto.
 19. A relay according toclaim 1, wherein the printed circuit card is made on the basis of glassepoxy or of ceramic.
 20. A relay according to claim 1, including a coversecured to the printed circuit card, in particular by adhesive.
 21. Arelay according to claim 1, wherein the coil is separate from the card.